Automatic analyzing and control system and apparatus therefor



,lune 23, 1931. A. c. HARRISON 1,811,233

AUTOMATIC ANALYZING AND CONTROL SYSTEM AND APPARATUS THEREFOR Filed July'7, 1924 2 Sheets-sheet 1 AUTOMATIC ANALYZING AND CONTROL SYSTEM ANDAPPARATUS THEREFOR' Filed July '7, 1924 2 Sheets-Sheet 2 fluor wegPatented June 23, 1931 UNITED STAT-Es ATENT oFF-ice ARCHIBALD C.HARRISON, F BIRMNGHAM, ALABAMA, ASSIGOR TO THE BROWN INSTRUMENT COMPANY,OF VPI'rTLAD:ELPTLEA, PENNSYLVANA" AUTOMATIC ANALYZING AND CONTROLSYSTEM AND -APPARATUS THEREFOR Application filed July -I,

The present invention relates to automatic analyzing and control systemsand apparatus therefor.

More particularly the invention relates to methods of control andapparatus applicable to the analysis and control of the ingredientsentering into various processes whereby continuous records of thepercentage of certain substances contained in the ingredients may mbeobtained, or in which the percentageof certain substances may beautomatically held to a constant predetermined value lWithin practicalvoperating limits; or in Which a record and the automatic control of thecon- 1 -tents entering into the process may be simultaneously attained.

The fundamental concept of the Vinvention comprises the generation of agas or'gases by areaction of a substance or substances to be '2Umeasured or controlled, or both, With a known chemically activesubstance Which will react therewith to evolve a gas in accord# ancewith fixed chemical laws. The gas evolved is utilized to effectthenecessary conz5trols, and depends upon four quantities; namely,pressure, volume, and temperature of the evolved'gases, and the rate ofbringing together the reacting materials.A By holding any three of thesequantities at constant v305 values, the variations in the fourth may beutilized for controland record purposes. ln the disclosure of thepreferred embodiments hereinafter set forth, the temperature and volumeof the evolved gases, and the rate of bringing together the reactingmaterials are held constant; While the pressure variations are reliedupon to effect the control, but it Will be plain tovthose skilled in theart any one of the other quantities enumerated may be 4d permittedtova'ry to effect the control.

The invention is applicable to a Wide range of processes. In fact it isapplicable to any processY involving a constituent substancer capable ofgenerating a gas or gases in deter- V minable manner when brought intocontact with any other substance or substances, Whether the lastmentioned substances enter into the process or not. For example, theinvention may be applied to control the manufacture of Portland cementby either dry beenheretcfore obtainable.

or Wet processes; the manufacture of sulphuric, nitric, hydrochloric andother acids or acid solutions; the manufacture of soda, potash,chlorine, ammonia, fertilizers, cya.-V

nides, alkalies, and many other uses. Y In any 55.;

An object ofthe invention is the provision. of methods and apparatusforfautomatically controlling a Wide range of'processes. A

l-inother object of theinvention is the provision of novel methods andapparatus for the mechanical performance of 1 chemicall analyses.v v

Further obj ects of the invention are theprovision of novelsampling,arrangements;-

the provision of novel control arrangements; the provision of novelsubcombinations of apparatus useful in relations independently ofthoselhereinaftersetforth; and such other j objects as may be attained bytheutilization so, of the various steps, sub-combinations, andiprinciples hereinafter set forth inthe description of preferredembodiments, and de-v fined in the appended-claims in the variousrelations to which they are adaptable by those l skilled in the art. Y

'Referring tothe dravvings- Y Fig. l isa sectional more or lessdiagrammatic vievv'shovving the essential details lof one type ofvmechanical analyzer operating 9a` oneform ofcontrol.

Fig. 2 is adiagrammatic `disclosure f of one form of circuit Which maybe controlled by the arrangement of Fig. 1. Y y

Fig. 3 is a diagram of a controll arrange- 95` ment for processes inwhich the response to.` the control is quick. y v Y Fig. 4 is ajdiagramof a control arrange-q ment for processes in which the response to c thecontrol is slow.

F ig. 5 is a diagrammatic disclosure par- Anala/eer structure andoperation The analyzer shown in Fig. 1 comprises an inclosed chamber 1with a funnel shaped bottom 2 provided with an outlet 8. A valve 4 foroutlet 3 is supported on a spindle which is slidably guided in support5. Support 5 is held in place by means of suitable brackets 6. Securedto the upper end of the spindle is a float 7. Covering float 7 is aconical hood 8 supported from chamber 1 by means of suitable strips orbrackets 9. A spiral trough 10 is secured in chamber 1 in any suitablemanner, with its lower end directly over the apex of hood 8, and itsupper end eo1nmunieating with the discharge opening of mixing chamber11.y Chamber llis secured in the upper part of chamber 1 and is providedwith inlet tubes 12 and 13 for the admission of the materials to bemixed. Suitable openings 14 for the escape of gases from trough l() andchamber 11 are provided. An orifice 15 for the escape of gases atpredetermined rates for differing pressures, is provided. The end ofVcontrol tube 16 extends into chamber 1 and the pressure variations inchamber 1 are transmitted through this tube to control suitableapparatus.

In operation the material to be analyzed is passed into the chamber 11preferably at a uniform rate through one of the inlet tubes 12 or 13.Through the other of the inlet tubes 12 or 13 a known substance orreagent which will react with the substance to be analyzed is passed ata predetermined rate in a manner to cause the evolution of a gas orgases in definitely determinable manner, and substantially in somedefinite relation to the proportions of the substance being analyzed.Compensation for temperature variations is preferably made by using anywell known form of device for automatically varying the resistance oforice 15, or the same effect may be attained by maintaining apredetermined temperature of chamber 1 in any convenient manner. Thequantity of materials passed into the ychamber 11 is so regulated, andthe relative proportions of materials and parts of the analyzer are sochosen that the gas evolving activity of the substance being analyzed.is substantially spent during the travel of the mixed materials downwardthrough spiral trough 10. Until a predetermined level of spent materialsaccumulates in the bottom of chamber 1, valve 4 will seal opening 3 andprevent the discharge of the spent materials. When the level issufficiently high, float 7 will raise valve 4 and permit the dischargeto proceed until the level drops sumeiently to permit valve 4 to close.It will be obvious that the spent product of reacting materials must.

be in liquid form to operate the valve. When4 both materials are solidsa solution of at least one, or if insoluble, a pulverized mixture of oneor both with a liquid, preferably water, may be prepared. Sufficientliquid to cause effective operation should be added and uniformity ofmixture may be obtained by the use of suitable mixture tanks containingagitators or stirrers. Preferably all solids are introduced by thismethod and fed into tubes 12 and 13 at uniform rates from constant leveltanks. This method of preparation is more fully set forth hereinafter inconnection with the description of Fig. 4.

The quanity of gases generated in the manner above set forth will beproportional to the quantity of substance sought in the material beingtreated. As the generated gas is permitted to escape through fixedorifice 15, the pressure in tube 16 will be proportional to thepercentage of the substance being sought or measured. lVhere it isdesired to analyze for more vthan one constituent material of a process,

a plurality of the analyzers may be utilized and in each the properreacting materlals to evolve the gases may be chosen.

Recording and control rEhe pressure variations in tubes 16 of theanalyzers may be utilized in many ways. Well known forms of gas operatedrecording thermometer structures may be utilized to make a continuousrecord of the pressure variations and the records so made may becalibrated to give direct percentage or quantity readings of the amountof the sought after constituent. Any form of gas operated recorder maybe so controlled. With a Bourdon tube connection, the needle of knowncontacting galvanometer recording or .control-arrangement may beactuated. The pressure variations may be utilized to vary the electricalresistance of a galvanometer circuit in any contacting galvonometercontrol o r recorder system, as for example, in the well known balancingpotentiometer recorders. Such automatic recording and control systemsfor the operation of valves, motors, switches, rheostats and variousmechanisms are well known, certain forms being set forth in U. S.Patents 713,258; 965,824; 1,125,699, and other patents, and are in widecommercial use.

In applying the invention to the control of continuous processes of theclasses hereinbefore mentioned, a representative sample the analyzer atwhich the control apparatus will be in a position of rest. f Wien anyva'- riation in pressure occurs in the analyzer it will be due `to achange in the desired preportions in the main process. The control.arrangements above enumerated are unbalanced and are set into operationinjaccord ance with the unbalance, and cause the op,- eration ofsuitable valves, motors, rhee'stats, weights, switches andthe like, tocontrol the relations in the main process in a manner to restore thebalance. Where liquids are to be controlled, valves are regulated in asuit able manner to Vary the flow of the proper constituents in the mainprocess; where sclids are utilized, weights may be shifted to vary therelative quantities thereof; where 'the change may be e`ected by furnaceteinperature adjustment, fuel valves or circuit makes may be actuated. Y

Referring to Figures 1 and 2, a novel form of motor control is providedwhich maybe vused to regulate Yvalves or shift Weights in response topressure variations in the analyzer, and which is adaptable tovprocesses in which Van appreciable time elapses from the operation ofthe-motors and the time when the changed proportions pass through theanalyzer. In this form, tube lconnects with a liquid reservoir 17 (Fig.1)', thebottom of which is connected by means of a tube 18 to a floatchamber 19. The levelof liquid'20 in chamber 19 varies with the pressurein tube 16 in obvious manner. A float 21 resting on ythe surface ofliquid 2O is linked to a pivot- `ally mounted arm 2 by means of asuitable 'tacts 30 'and 31 are secured to fixed supports (not shown)yad] acent to disc 24 and in a -pos'ition to be engaged respectively bycontacts ,28 and 29 when disc 24 is rotated by motor 27. Arm 22 (Fig. 2)is connected by conductor 32 to one terminal of battery 33. The Votherterminal of battery 33 is connected by a conductor 34 to terminals ofelectromagnetici switches or relays 35, 36, 37 and 38. The remainingterminals of these relays are connected respectively by conductors 39,40, 41 and 42, to contacts 28, 29, 30, and 31. Relay 35, when energized,through its armature' 43 closes a'circuit from conductor 44 ofapowerline, through its front contact, conductor 45 throughthe motor 27 to theother power supply conductor 46, causing-motor 27 to rotate Vdisc 24 incounter-clockwise direction. Relay '36 .when energized,'throughitsarmature 47 closes a circuit from supply conductor 44,conductor 48, motor 27 and conductor 46,

.causing motor 27 to rotate disc 24 in a clockwise direction. Relay :37,when energized, closes a circuit through its armature 49 .from

lline conductor 50, conductor 51,*motor 52,

and line conductor .53, causing rotation of motor 52 injone direction.Relay 38 controls a circuit through its armature 54 from line conductor50, conductor 55, motor 52, and A line conductor 53, causing a reverserotation f of motor 52.Vv Motor 52 may drive a valve, or weight shiftingarrangement or the like.

With the'parts in the position shown in' Figures 1 and 2, the system isbalanced and no movement of the motors occurs.. The flow `of materialsin the process being controlled will continue at uniform rates untill achange in the proportion of the substance beingcontrolled or regulatedoccurs. This change may occur due to lack ofuniformity in quality of thematerials. in the main process, or for other reasons.. As soon Vasainaterial change occurs in the Vsampled portion passing through theanalyzer, tlie'pressure in chamber 1 will change, causing a changeinvthe level of the liquid 2O in the float chamber.' VVThis will result inthe shifting of arm 22 into engagement with Contact 28 or 29 on discV24. lf thev pressure decreases', contact 28 will be engaged causingenergization of magnet 35 and closing the circuit through armature 43 tomotor 27.V Motor 27 willV nowrotate disc 24 counter-clockwise, carryingcontact 28 into engagement with contact 30, and completing A'the circuitto energize magnet 37 Energize,-l tion of magnet 37 closes the' circuitVfor motor 52 causing rotation in a direction to increase the percentageof thecontrolled substance.

The rotation ofniotor 27Fwill continue until the contact 28 isdisengaged from arm 22, vbreakingthe circuits of magnets 35 and 37.

Magnets 35 and 37 will then de-energize opening the circuits of motors27 and 52 and stopping the rotation thereof. The proportions of thematerial in the nia-in process will now be changed, but until thechanged'.` proportions reach the analyzer, Contact 28 will engagecontact 30. ANow asthe change becomes eective, arm 22 will'drop as thefloat rises due to the increased` analyzer pressure and willengagecontact 29. rlhis completes the circuit for. magnet-or switch 36 whichwillV energize and closeV the reversing circuit through its armature 47for motor 27 causing disc 24 to rotate clockwise. This rotation of motor27 will continue while motor 52 remains at rest until arm 22 passes thebalancy ing or zeroposition due to an increase in the proportion of thecontrolled substance over the desired amount. When this occurs disc 24will be rotatedto the` position. where con- 'tact 29 will engage Xedcontact 31 causing y energizati'on of magnet'38 and av reversal of vzeroposition.

'rotation of motor 52. The reverse operation of motor 52 will continueuntil contact 29 is disengaged from arm 22 and will decrease theproportion of the controlled substance causing an upward movement of arm22. It will be noted that a step by step rotation will be caused inmotor 52 and the length of the steps or intervals of rotation will varywith the deflection of arm 22 from the balanced or The amountofcorrection in proportions caused by motor 52 will accordingly vary withthe amount of deviation in pressure from the value indicating thepresence o' the desiredproportions. By causing each step to apply acorrection in proportions suiiicient to bring` the arm 22 back to thezero position, the desired relative proportions of the chemically activesubstances may be closely maintained. ln practice for most processes, itis found that commercial materials vary suihciently in quality so thatthis relation of correction cannot be maintained. It is, however,possible in al1 cases to correct slightly more than the desired amountto allow for variations in quality of the mate-V rials so that acontinual hunting motion will be set up, the limits of which are wellwithin the permissible variation of commercial linished products of theprocesses. In all cases more uniform and higher grade finished productthan has heretofore been possible may be automatically attained.

Although relays have been indicated to control the motor circuits, itwillbe understood that any well known arrangement of Yelectro-ma,g,netic switches may be utilized, or

for small motors, the circuits may be made directly by arm 22 withoutthe utilization of relaying apparatus. lt will also be understood thatarm 22 may be actuated by a Bourdon tube connected to tube 16, or by a.galvanometer arrangement controlled by the pressure variations in tube16, and that various forms of reversing motors; are adaptable for use inthe system.

In processes where the response in the analyzer to changed proportionsis rapid, as in the case of mixing liquids, a simplied controlarrangement may be utilized. Such an arrangement vis shown in Fig. 3.The motor 27 and rotating disc 24 are eliminated and magnets or switches37 and 38 control motor 52 in the manner above set forth to regulate theproportions of the materials in the main process. Fixed contacts 30 and31 are adapted to be engaged by arm 22 which will complete circuits frombattery 38 to relay 37 or 3S depending upon whether contact 30 or 81 isengaged. Arm 22 may be actuated in any convenient manner by the pressurevariations in the analyzer. As shown, arm 22 is secured to a pivotallymovable coil 56 of a galvanometer and is arranged for movement betweenthe magnetic poles 57 and 58. The coil 56 may be actuated by a springtending to throw arm 22 to one side or the other. An energizing circuitfor coil 56 includes a battery and a high resistance conductor 6() whichmay dip in a loop into a tube 61 partially lilled with mercury 62. rPheother end of tube 61 is connected to tube 16 of the analyzer. lnoperation, when a balanced condition exists, the mercury 60 is at alevel where the resistance of the galvanometer circuit is such as willcause sufficient current to flow to hold arm 22 cenrally betweencontacts 30 and 3l against the spring tension. A decrease in p'ressureinthe analyzer will cause the level of mercury in k61 to drop, increasingthe kresistance of the galvanometer circuit and causing a decrease ofcurrent. Arm 22 will then move under the influence of the coil springinto engagement with contact 30 causingv energization of magnet 3.7 anda corresponding rotation of motor to increase the proportion of thecontrolled substance. y Motor 52 will continue to rotate until arm 22 isreturned to the balanced or zero position. As in this Yform the responsein the analyzer to changed. proportions is rapid, when the. properproportions are restored arm22 will be posi- 30 and 31. In similarmanner, when the proportion of the-controlled substance becomes toolgreat the mercuryivill rise in tube 6l, decreasing the resistance andincreasing the current flow in the galvanometer circuit. Arm 22 willthen engage contact Sland causeenergization of magnet 88 which willcause rotation of motor 52 to decrease the proportion of the controlledsubstance. lt will be seen that as soon'as any deviation from the properproportion of theV controlled substance occurs, motor 52'will be setinto operation to restore the proper relative values.

In Fig. l, a modiiied form of control disclosed for utilization where itis desired to establish a definite timing between correctvingrsteps.This form is useful in processes where a comparatively long timeelapsesbetween a cha1igg'e'otl proportionsof the materials and thecorresponding effect in the analyzer. A timing control is accordinglyintroduced so that after an adjustment is mad-e, the'system willbeconditioned for the vnent adjustment only after a sufficient intervalhas ela sed to nermit the 1oro Jortions l) l i l .of the precedingadjustmentto be passing through the analyzer. Jarm 22 is secured to coil56 and actuated by the galvanometer arrangement as set .forth inconnection with Fig. '3, although the float arrangement of Fig. 2, or aBourdon tube arrangement might obviously be utilized.

Secured to arm 22 and properly insulated therefrom, are contacts 63 and64 to which are secured power-supply conductors 65 and 66. Mounted forrotation on the axis of movement of arm 22 but movable independj toconductors -102 and .103 by contacts ..98 -and ently of arm 22 is amember 67 provided With .a toothed rack extension 68 and arms 69 and 7 0formed integrally'therewith. Worm 26, driven by motor 27, meshes withand drives rack 68 together with arms 69 and 70. Con- -tacts 71 and 72are secured to arm 69 and insulated therefrom, and contacts 73 and 74are secured to and properly insulated from arm 70. 'Contacts 71 and73are adapted to engage contact 63, and-contacts 72 and 7 4 are adaptedto engage yContact..64 When ,arm 22 is shifted -to the right andwleftrespectively. Contacts 75, 76", 77 andi' 8 are. secure-d to fixedsupports .and positioned to :be engaged by contacts 71 .and 72 or 73 and74 as arms 69 -and 70 are rotated to the right and left respectively, bythe action of motor 27. .Con tacts 71 and 74 .are connected byconductors 7 9 to one terminal of the armature Winding ofmot'or 27.Contacts 72 and 73 Aare connectedby conductors 80 to the other terminalof motor l27. The `4field terminals 81 `and 82 of motor 27 are.permanently .connected .to a source of electrical energy. Contact isconnected 4directly .to .one armature terminal of motor .52 by conductor83; andcontact 76 is Aconnected by conductors 84 tl rough contact 85 .ofan .armature 86 to ythe .other armature terminal of motor V52. The4field Yof motor 52 is connected permanently toa supply of electricalenergy by leads 87 and 88. Armature 86 is pivotally mounted at89and isactuated by aspring 90 and a magnet 91. Magnet .91 is connected byconductor 92 in series .through armature 93 of a rela-y 94, and timeswitch .9.5 ft'o the yopposite poles of an .electrical .supply source. Arotating cam 96er any other suitable means is utilized'to periodicallyclose switch 95. Relay94is connected .in series in line lead 66 throughan insulated'contact 9.7 on armature 86. `Mounted on armature 86 .are,insulated .contacts 98. and .99, which are connected to the oppositepoles of asource ofelectrical energy by conductorslOO and 101.`W'henmagnet'91 is energized, vcontacts 98 and 99 Will apply linepotential to contacts 7 5 and V78 and 7 Gland 77 through conductors 102.and .103 respectively, and contacts 85 and contacts 97 Will be open.Contacts 77 and 78 are connected byconductors 104 and '105 to conductors84 and 83.

YIn operation, cam 96 actuates svvitch`95to periodically close andinterrupt 'the Venergizing-circuit for lmagnet 91. Vfithrth'eproportions ofimaterials being'controlled in the processatrthepropervalues, arm 22 will ,be insthezero position shovvnin Fig. .4. .Asmagnet911i-senergizedcontacts V85..and 97 Will be interrupted andlinepotential will be applied 99, but =the Aenergizing circuit' of motor 52is .open at Contact 85 .fand no 'operation of that motor can. occur inany possible position ofarm .22. i So longas the arm 22 .isin neutralposition, motor ,2.7 will Vnot be; op-

erated when magnet 91 is' energized. When ythe pressure in the analyzerdecreases, arm 22 will shift to the right, causing contacts 63 and 64 to`apply line potential te contacts 71 and 72. As soon thereafter asmagnet 91 cle-energizes, armature ..86 will Vclose contacts 85 and 97and mo-tor 27 willjreceive armature current from. contact 71,conductor 79, the motor armature and .conductor to contact v7 2. Motor 27 willrotate in a directionte move arms `69 and 70 fto ythe right causingcontacts 71 and 72 to engage contacts 7 5 and 76. Energy is novvsupplied to motor 52l from contact 63, .contact 71, contact 75,conductor 83, motor 52, conductor 84, contact y85, Yconductor 84,contact 76, contact 72 and contact 464. Motor 52 will rotate in adirection to .correct the relative .proportions vof materials in theprocess, land the rotation of .both ymotors will continue until contacts71 and 72v are moved out vof engagement with contacts 163 andA 64 atwhich time the armature circuits vof both motors Will vbe broken. Whilecurrent flows in conductor 66, relayj-94 Will be energized and Will.attract armature 93 .to interrupt vthe energizing circuit of magnet 92so that the .correcting steps will be carried on Without interruption byoperation of the .time control. After the interruption of the motorcircuits, relay 94 Willde-energize and contacts 71 and 72 will ybe inengagement with contacts 75j and 76. Upon the lnext closure of switch95, magnet 91 Will energize interrupting contacts and 97, and closingcontacts 98 and 99. A circuit Will now be completed from contact 98,conductor`102, contact 75, contact 71, conductor 79, motor 27, conductor83, contact 72, contact 76', conductor 103, and contact 99. Thecurrentdirection in this circuit Willk be such as vto reverse the rotation ofmotor 27, and this rotation Will continue until contacts 71 and yhascompleted the restoring movement and magnet 91 has'de-energiz'ed, arm 22Will vhave adjusted'itself -to the changed proportions, and contacts 63and 64 Will engage contacts 71 and 72 causing a repetition of the cycleabove set forth, vand further correction will. occur. The cycles Will-berepeated until the properproportions are restored in the 'process whenarm A22' 'will'. return to normal.l In a similar manner, if theproportions change so that too muchpressure iS. Zcneratedinthe analyzer,arm 22 will shift to the left causing contacts 63 and 64 to engagecontacts 73 and 74. This will complete an energizing cicuit overconductors V79 and 80 in a direction opposite to that closed overcontacts 71 and 72, and motor 27 will rotate arms 69 and 70 to the leftcausing engagement of contacts 73 and 74 with contacts 77 and 78. Acircuit will now be completed over conductors 104 and 105, to 83 and 84,causing motor 52 to rotate in a direction to decrease the proportion ofthe controlled subst-ance in the process, and to cause a decrease inanalyzer pressure. Rotation of motors 52 and 27 will continue untilcontacts 7 3 and 74 are disengaged from contacts 63 and 64 when thesupply of enero'y from conductors 65 and 66 will be interrupted. Asabove set forth, relay 94 will cle-energize, permittingl switch 95 tocause energization of magnet 91 at the proper time. When magnet 91energizes, a circuit for motor 27 will be closed from contacts 98 and99, over conductors 102 and 103, contacts 7 7 7 3, 78 and 74, conductors79 and 80 to motor 27. Motor 27 will rotate the contacts 73 and 74 tothe right -until they are disengaged from contacts 77 and 78,interrupting the energizing circuit as traced. If the correction wasinsufficient to effect the restoration of arm 22 to zero position, thecycles will be repeated until the balance is eifected.

It will be noted in this form that the extent of correction will varywith the deflection of arm 22 from the zero position, and willaccordingly vary with the degree of deviation from desired proportionsin the process. llt

ill also be noted that correction continues in steps until the desiredconditions are restored.

, 114 is provided in the hopper and the Sampling and regulation ofprocess utz'leag solids The application of one form of the invention tothe control of a process handling solids is shown in Fig. 5. Forpurposes of illustration the control of carbonates in the manufacture ofPortland cement by a day process will be described. As is well known.the Portland cement may be manufactured by mixing definite proportionsof lime stone with shale in a. manner to produce a mixture containing asnearly as possible a fixed percentage of calcium carbonate, andt'reating this mixture to produce the cement. ln

it is highly desirable to maintain a definite percentage or proportionof carbonates in the materials, and this may be accomplishedautomatically in the following manner.

A feed hopper 110 for crushed shale is arranged over'an endlesstraveling conveyor 111 driven and supported by pulleys or sprockets 112and 113. A discharge opening area of the opening is controlled by a gate115. Gate 115 is connected to and movable with one end of a scale beam116 which vin turn isV fulcrumed at 117. Mounted directly over thefulcrum 117 is motor 52, which is arranged to drive a weight adjustingscrew 118, rotatably supported in journals 119 from the scale beam 116.A sliding weight 120 is driven by screw 118 in a manner to be shifted tothe right or left along the scale beam in accordance with the rotationof motor 52. Connected to the scale beam 116 by a linkv 121 is a member122, pivotally mounted on a fixed support 123. Supported on the otherend of 122 is a roller 124 over which the endless conveyor belt 111runs. In operation the weight of the material on the belt 111 movesscale beam 116 upward and gate 115 downward until a balance isestablished between the weight of material passing continuously over thebelt, and the adjustment of weight on the scale beam. A shifting ofweight 120 to the left permits gate 115 to lower, reducing the amount ofmaterial carried continuously out through opening 114; and movement ofthe weight to the right raises gate 115 and increases the weight ofmaterial passing continuously out of the hopper. A similar h0pper 125with an opening 126, a conveyor bottom 127 mounted on and driven bypulleys 128 and 129` and a control gate 130 is provided for thecontinuous feeding of carbonates or crushed lime stone. Gate 130 isconnected to and actuated by a scale beam 131, fulcrumed at 132 andprovided with adjustable weights 133 and 134. Connected to bea-m 131 bya link 132 is aV member 133. Member 133 is pivotally mounted at 134 andsupports a roller 135 over which conveyor 127 moves. In operation theposition of gate 130 and accordingly the amount of material passing outof opening 126 on belti127 is determined by the weight of the materialand the setting weights on the beam. For each setting of the weights,the gate 130 will lassume a definite position and a balanced conditionwill be established until either the adjustments of weights 133 and 134are changed manually. or the density of the material on the beltchanges. il

By the arrangements set forth, for a given setting of the weights;crushed shale from hopper 110 and crushed limestone from hopper 125 willbe fed into the conveyor 136 at al substantially uniform and controlledrate. From conveyor 136 the mixed shale and limestone pass through .adryer 137 of any well known construction. From the dryer, the materialspass through conveyor 138 into grinder 139 and the ground materials arethen discharged into conveyor 140. A small sampling conveyor belt orchain 141, provided with flights 142 is supportedon and drivenbysprockets or pulleys 143 and 144 in a manner to dip into the groundmaterials passing through conveyor 140 and picks up vinto tank 152.

Asmall'. amounts thereof inthe flight'pockets.

the bottom ofthe plane'147v the screened material is caught on anendless traveling conveyor belt 148 supported on and driven by pulleys149 and 150. 'Positioned atvthe right end of the inclined plane 14'? isan adjustable control member or gate 151, the

lower edge of which levels off the material on 'belt 148 and determinesthe amount which may be carried to the" right and discharged In thismanner fine sifted material is passed continuously into tank 152 Vat auniform rate. The surplus material scraped off belt 14S by the action ofgate 151, andthe coarse material whichpasses through th-e center of thescreen 146 drops intofhopper -or casing 153 and are returnedto conveyor140 passing onto the kilns. Rotatably supported in tank 152 and drivenby a belt 153 is an agitator or .stirrer 154. Water from a pipe 155 iscontinuously fed into a constant level tank 156 provided withl anoverflow outlet pipe157. A discharge pipe158 feeds -water at a constantrate'into tank 152, due

tothe constant level'which is maintained Vin tank A155. Tank 152 isprovided with an overflow outlet 159 whichr maintains a constant levelintank 152. Stirrer 154 thoroughly mixes the material from conveyor-148with the water and maintains the contents-of 152 in a constant stat-e ofagitation. 'Aunif-orm and continuous low off-themix'ture 'of water andfine materials is withdrawn from tank 152 through tube 160 and isintroduced Yinto the'analyzer through tube 13. A uniform flow of anyproperacid is intro-duced into `the trolled by'pressure variations inthe analyser -asfabove set forth, and positions weight 120 along beam116 in a manner tomaintainthe percentage of CaCO3 in the materialYpassing into the kilns at asubstantially constant value by increasing or'decreasing the amount of shale fed from hopper 110 while the limestoneis fed at a'uniform rate If desired, the feed of the limestone may bevaried, and the feed of shale held constant, or by the addition of amotorfor shifting weight 133, the feed from each hopper may besimultaneously varied. It will also be apparent that any suitableautomatic feed arrangement may be substituted for the arrangementsshown. Such devicesordinarily varv with the material to be handled, and

theumethod of applying the present inventiony tothe various knownarrangements will be apparent to those skilled in the art. It is to Y beunderstood that the invention is not limited to the diagrammaticarrangements shown and that the disclosures are illustrated of forms ofthe invention which may be varied widely-without departing from thespirit of the invention as defined by the terms ofthe appended claims.Yl

Subject matter of invention disclosed but not claimed in the presentapplication, is disclosed and claimed in my copending appli-V cation,Serial No. 233,727, filed November 16,'l

1927, for Control methods and apparatus.

Having described preferred embodiments of the iiivention,.what isdesiredto be secured by Letters Patent and Vclaim-ed as new is:

1. ln a process Vfor treating materials, comprising a constituent orconstituents which may be treated in a' manner to cause ythe evolutionof a .gas or gases, `the -method of determining the V"amount of saidconstituent or constituents which comprises the steps ofcontinuously'treating a chemical sample of the materials to cause saidconstituent or constituents to evolve gases in predetermined manner andcontrolling'suitable apparatus by the variations ina physicalcharacteristic of the evolved gases.

2. The method of controlling processes of treating materials embodyingsubstances capable of reacting to cause evolution of gases, whichcomprisestreating chemical samples of the materials to cause theevolution of gases in accordance with the proportions yof the saidsubstances contained therein, and

varying therelative proportionsof'the subl stances in the material underthe control of the vvariations in a physical characteristic of theevolved gases.

,3. In a process for; treating materials, comprising a constituent orconstituents which may be treated in a manner to causetheevolution ofagas or gases, the method of controlling the amount of said constituentor constituents which comprises continuously treating achemical sampleofthe .materialsfto cause the evolution of gases-from said constituentVor constituents contained therein, and varying the proportions of theconstituents in thematerial under the controlof the variations in aphysicalcharacteristic of the levolved gases.

4. |The method of analyzing materials-containing constituents capable ofentering into gas evolving reactions with knownV substances indeterminable manner. which comprises'the steps oftreatingcheinicalsamples of the materials to be analyzed with suitable reactingysubstances to evolve gases in predetermined manner, andoperating-suitable control apparatus under the Vcontrol of `variationsin a physicalcharacteristic ofi-the evolved gases.

5. The method of analyzing materials containing constituents capable ofentering into gas evolving reactions with known substances indeterminable manner which comprises the 'steps of treatingthe materialsto be analyzed with suitable reacting substances to evolve gases inpredetermined manner, and operating suitable control apparatus under thecontrol of variations in a physical characteristic of the evolved gases.

6. A process which comprises the steps of continuously treating inpredetermined manner a material containing a substances of unknownproportions with a 1xnown substance which will react chemicallytherewith, to evolve gases in known manner, and operating suitablecontrol apparatus under the control of variations in a physicalcharacteristic of the evolved gases.

7. A method as set forth in claim 6 in which the evolved gases arecontrolled in a manner to cause pressure variations in accordance withvariations inproportion of said iirst mentioned substance in saidmaterials.

8. A mechanical analyzer comprising gas generating means, means fordischarging the gases from said generating means in predeterminedmanner, and control means operated by the pressure variations in saidgenerating means.

9. In a cont-rol system, a gas generator, and control apparatusmaintained at rest when gases in said generator are evolved at apredetermined rate; said control apparatus being initiated in operationby substantial deviat-ions from said predetermined rate of evolution ofgases to restore the rate of evoluti-on to the predetermined value.

l0. In combination, a gas generator; means for feeding materials to saidgenerator in a manner to cause continuous evolution of gases; and meanscontrolled by pressure of the evolved gases for maintaining the rate ofevolution of said gases in said generator substantially at apredetermined value.

11. The combination as set forth in claim 10, in which said lastmentioned means comprises means for varying the relative proportions ofthe materials being fed to said gas generator.

12. The combination as set forth in claim 10 in which said lastmentioned means comprises automatic switching apparatus, and a reversingmotor controlled by said switching apparatus.

13. In combination, means for feeding materials into a main treatingapparatus in definite proportions; means for continuously sampling saidmaterials as they pass into said main apparatus; and means formechanically analyzing said sampled portions to determine the proportionof a constituent part thereof and for automatically controlling saidfirst mentioned means in accordance with the results of said analysis ina manner to maintain substantially uniform proportions of saidconstituent part of the materials being fed into said main apparatus.

14. The combination as set forth in claim 13 in which said lastmentioned means comprises a gas generator in which said sampled portionsare treated in a manner to cause the evolution of gases, together withmeans controlled by said gases for controlling said first mentionedmeans.

15. The combination as set forth in claim 13 in which said firstmentioned means comprises automatic weighing apparatus.

16. In a process for the manufacture of compounds from materialscontaining constituents capable of reacting with a known -substance toevolve gases, the steps of automatically and continuously mixing thematerials, continuously withdrawing samples of the mixture andsubjecting the same to reactions with said substance to cause evolutionof gases; and controlling the mixture in accordance with the evolvedgases to maintain predetermined proportions of said constituentstherein.

17 A process for the manufacture of cement comprising the steps ofautomatically mixing limestone and shale, continuously sampling aportion of the mixture and subjecting the same to reactions with a knownsubstance to cause the evolution of gases from the carbonates containedtherein; and continuously controlling the mixture through variations inthe quantity of the evolved gases in a manner to maintain substantiallyfixed proportions of the carbonates therein.

18. The method of controlling a process of treating materials whichcomprises the step of chemically analyzing a portion of materialsentering into the process, and controlling the process by the variationsin a physical characteristic of one of the products of the chemicalanalysis.

19. The method of controlling characteristics of a mixture of substanceswhich comprises withdrawing a portion of the mixture, reacting thewithdrawn portion with a substance causing the formation of gaseousreaction products, and controlling the mixture of the substances by thevariations in a physical characteristic of the gaseous reactionproducts.

In testimony whereof, I afIix my signature.

' ARCHIBALD C. HARRISON.

